Charak Samhita
दोषातिमात्रोपचयात् स्रोतोमार्गनिरोधनात्। सम्भवत्युदरं तस्मान्नित्यमेव विरेचयेत् ॥६१॥
॥ Post virechana regimen॥ Udara is caused due to the obliteration of the body channels leading to accumulation of morbid dosha. Hence udara should be treated by regular virechana (therapeutic purgation).
english translation
doSAtimAtropacayAt srotomArganirodhanAt। sambhavatyudaraM tasmAnnityameva virecayet ॥61॥
hk transliteration by Sanscript